Minimally invasive techniques and instruments for placement of intraluminal medical devices have developed over recent years. A wide variety of treatment devices that utilize minimally invasive technology have been developed and include stents, stent grafts, occlusion devices, infusion catheters and the like. Stents—frame-like structures placed within a body vessel to provide support to and maintain patency of the vessel—became especially popular with the introduction of coronary stents to the U.S. market in the early 1990s. Since that time, both coronary and peripheral stents have been proven to provide a superior means of maintaining vessel patency, and have become widely accepted in the medical community.
The use of stents has been extended to treatments that target other body vessels. For example, bile duct stents, ureter stents, and esophageal stents are now widely used to maintain patency of each of these bodily passages. Esophageal stents, for example, are sometimes used to maintain patency of the esophagus from a point within the vessel, such as in the treatment of a stricture that threatens closure of this vessel.
Stenting of the esophagus provides unique challenges not faced by stents intended for other vessels, such as vessels of the vasculature. For example, the lower esophageal sphincter—a muscle near the junction with the stomach—is normally closed to block stomach acid from entering the esophagus. Normally, this muscle only opens during swallowing to allow food to pass into the stomach. After a stent is placed across this muscle, however, the sphincter can remain open in response to the intraluminal support provided by the stent, reducing the ability of the muscle to block acid entry into the esophagus. Over time, acid passage into the esophagus can cause tissue damage, aspiration pneumonia, and other undesirable outcomes.
Thus, a need exists for improved medical devices for modifying the flow of material and/or fluid through a bodily passage.